Measurement of the first ionization potential of astatine by laser ionization spectroscopy

レーザ分光法を用いたアスタチンの第一イオン化ポテンシャルの測定

Rothe, S.*; Andreyev, A. N.*; Antalic, S.*; Borschevsky, A.*; Capponi, L.*; Cocolios, T. E.*; De Witte, H.*; Eliav, E.*; Fedorov, D. V.*; Fedosseev, V. N.*; Fink, D. A.*; Fritzsche, S.*; Ghys, L.*; Huyse, M.*; 今井 伸明*; Kaldor, U.*; Kudryavtsev, Yu.*; Kster, U.*; Lane, J. F. W.*; Lassen, J.*; Liberati, V.*; Lynch, K. M.*; Marsh, B. A.*; 西尾 勝久   ; Pauwels, D.*; Pershina, V.*; Popescu, L.*; Procter, T. J.*; Radulov, D.*; Raeder, S.*; Rajabali, M. M.*; Rapisarda, E.*; Rossel, R. E.*; Sandhu, K.*; Seliverstov, M. D.*; Sjdin, A. M.*; Van den Bergh, P.*; Van Duppen, P.*; Venhart, M.*; 若林 泰生*; Wendt, K. D. A.*

Rothe, S.*; Andreyev, A. N.*; Antalic, S.*; Borschevsky, A.*; Capponi, L.*; Cocolios, T. E.*; De Witte, H.*; Eliav, E.*; Fedorov, D. V.*; Fedosseev, V. N.*; Fink, D. A.*; Fritzsche, S.*; Ghys, L.*; Huyse, M.*; Imai, Nobuaki*; Kaldor, U.*; Kudryavtsev, Yu.*; Kster, U.*; Lane, J. F. W.*; Lassen, J.*; Liberati, V.*; Lynch, K. M.*; Marsh, B. A.*; Nishio, Katsuhisa; Pauwels, D.*; Pershina, V.*; Popescu, L.*; Procter, T. J.*; Radulov, D.*; Raeder, S.*; Rajabali, M. M.*; Rapisarda, E.*; Rossel, R. E.*; Sandhu, K.*; Seliverstov, M. D.*; Sjdin, A. M.*; Van den Bergh, P.*; Van Duppen, P.*; Venhart, M.*; Wakabayashi, Yasuo*; Wendt, K. D. A.*

The radioactive element astatine exists only in trace amounts in nature. Its properties can therefore only be explored by study of smallest quantities of artificially produced isotopes or by performing theoretical calculations. One of the most important properties influencing the chemical behaviour is the energy required to remove one electron from the valence shell, referred to as the ionization potential (IP). Here we use laser spectroscopy to probe the optical spectrum of astatine near the ionization threshold. The observed series of Rydberg states allowed the deduction of the IP of the astatine atom for the first time. New ab initio calculations were performed to support the experimental result. The measured value of IP(At) serves as a benchmark for quantum chemistry calculations of the properties of astatine as well as for the theoretical prediction of the ionization potential of super-heavy element 117, the heaviest homologue of astatine.